Lubricating compositions



Patented Jan. 4, 1966 3,227,652 LUBRICATING COMPOSITIONS Arnold W.Ackerman, Middletown, Conn, assignor to Anderson Oil and ChemicalCompany, line, a corporation of Connecticut No Drawing. Filed Nov. 18,1963, Ser. No. 324,239 8 Claims. (Cl. 252-495) This application is acontinuation-in-part of my copending application Serial No. 784,453,filed January 2, 1959, now abandoned.

This invention relates to fluid lubricating compositions and, moreparticularly, to water-base lubricating and cooling fluids which aresuitable for use in metal-forming, grinding, and machining operations.The invention is based on the discovery that small quantities of ahomopolymer of ethylene oxide having an average molecular weight of notless than 100,000, when incorporated either in water-base chemical or inWater-base soluble-oil lubricating compositions, are capable ofincreasing the viscosity and imparting hydrodynamic lubricity to theselubricants without diminishing their inherent cooling properties,chemical lubricity, or altering their superior extreme pressure,antiwear, and antiweld properties.

Water-base chemical lubricating compositions, which are designated assuch because they usually contain only boundary lubricants to impartchemical lubricity, were primarily developed as substitutes for oillubrication in high-speed machining operations, where boundarylubrication is suflicient and rapid dissipation of the high frictionalheat generated is of paramount importance. Although waterbase chemicallubricating fluids possess chemical lubricity as well as excellentextreme pressure, antiweld, and antiwear properties, these fluids areinferior to compounded cutting oils for many types of slow-speed andheavy-duty machining operations, such as threading, tapping, andbroaching, which require hydrodynamic or quasi-hydrodynamic lubricity.Other water-base lubricating fluids possessing both quasi-hydrodynamiclubricity and chemical lubricity, such as the soluble-oil lubricatingcompositions which are composed primarily of stabilized oil-in-wateremulsions of a petroleum-base oil and a boundary lubricant, have alsoproved interior to cutting oils for slow-speed machining operations.Where, however, a small quantity of a homopolymer of ethylene oxidehaving an average molecular weight of not less than 100,000 is dissolvedin either a water-base chemical lubricating fluid or in a water-basesoluble-oil lubrieating fluid, both of which contain boundarylubricants, the lubricating properties of the water-base fluids areimproved to such a great extent that they are superior to cutting oilsfor all types of metal-forming, grinding, and machining operations.

Therefore, up until the time of the present invention, the water-baselubricating compositions mentioned above were advantageously usedprimarily only in certain industrial applications, such as high-speedmachining operations wherein two fundamental requirements were ofprimary importance: (1) rapid dissipation of high frictional heat, and(2) extreme pressure, antiweld, and antiwear properties (a function ofthe boundary lubricant additive). In heavy-duty machining operationsonly the cutting oils could be used. These cutting oils, unfortunately,lack some of the advantageous properties associated with waterbaselubricants. For example, the cutting oils are less eflicient coolantsthan the water-base lubricants. This cooling property of the water-baselubricants contributes to dimensional accuracy, comfortable handling ofwork, and reduction of gross heat strain.

It was hoped that one day it would be possible to obtain a new,versatile type of lubricant, which possessed not only all the advantagesof the cutting oils, but also all the advantages of the water-baselubricants. The present invention provides such a lubricant for thefirst time. Although it is still a water base lubricant, having theadvantageous properties of the usual water-base lubricants, it alsopossesses all the advantageous features of the cutting oils and can beused as an improved replacement for the cutting oils.

This new modified water-base lubricant is achieved by merely adding theethylene oxide homopolymer mentioned above to a water-base lubricant.Unexpectedly, such addition of the homopolymer does not diminish theinherent desirable properties of the water-base lubricant. Instead, thestep of adding the homopolymer simply increases the viscosity of thewater-base lubricant and this increase in viscosity is all that isneeded to give the water-base lubricant all of the additional desirableproperties attributable to cutting oils. It was completely unexpectedthat such a combination of properties in a lubricant could even beachieved, particularly by such a single simple stop. And it was alsocompletely unexpected that this single simple step would impart to awater-base lubricant an entirely new use in that it can now be used inan area Where only cutting oils heretofore were useful.

The water-base lubricants to which the ethylene oxide homopolymer ofthis invention is added, are of course well-known. Although theselubricants have at times contained various polymers with low molecularweights, these low molecular weight polymers were used only as boundarylubricants and were not used for the purpose of increasing the viscosityof the water-base lubricants. There had been no reason to increase theviscosity of the water-base lubricants heretofore, because it was notknown that the viscosity could be increased Without sacrificing theinherent advantageous properties of the water-base lubricants. Indeed,it was not even believed that it would actually be advantageous toincrease the viscosity of the water-base lubricant.

It had been previously proposed to employ a low molecular polymer in awater-base lubricant system, the polymer functioning as a boundarylubricant. The polymer was not meant to, and did not, functionas aviscosity-increasing agent. In fact, the use of low molecular weightpolymers had a negligible effect on viscosity as far as the presentinvention is concerned. For example, a 2% water solution of apolyethylene glycol polymer (manufactured by Union Carbide Corporationunder the trade name Carbowax, and having a molecular weight of about6000) at F. has a viscosity of only about 1.12 centistokes, whereas theviscosity of a 2% water solution at 100 F. of the ethylene oxidehomopolymer of the present invention may have a viscosity of from 40 to12,000 centistokes. The difference in viscosity between the lubricantsof this invention and the previous lubricants which contained lowmolecular weight polymers as boundary lubricants is not a difierence indegree, but a difference in kind. Itis because of this difference that anew lubricant is achieved. The new lubricant possesses entirely newproperties which permit, for this first time, a water-base lubricant tobe used as a complete substitute for cutting oils. See, for example,Beaubien Patent No. 2,825,693, wherein low molecular polymers areemployed as boundary lubricants, that is, to impart extreme pressure,antiweld, and antiwear properties to the lubricant. This type oflubricant, as described above, would have an extremely low viscosity ascompared to the present water-base lubricant. It would therefore possessonly the advantages of a water-base lubricant rather than the advantagesof both a water-base lubricant and a cutting oil.

The invention, therefore, provides an improved waterbase fluidlubricating composition which is adapted to provide, upon dilution withwater, lubricating fluids suitable for use in metal-forming, grinding,and machining operations. Basically, this lubricating compositioncomprises a major amount of water, a minor amount of a boundarylubricant suificient to impart chemical lubricity to the composition,and a minor amount of a homopolymer of ethylene oxide having an averagemolecular Weight of not less than 100,000 sufificient to contributehydrodynamic lubricity to the composition. These waterbase lubricatingcompositions, as well as the lubricating fluids prepared by furtherdilution of the composition with Water, possess both chemical andhydrodynamic lubricity. The general lubricating properties of thewater-base lubricating compositions of the invention and of thelubricating fluids prepared from them by further dilution with waterhave been found superior in every respect to those of compounded cuttingoils, allowing the waterbase lubricants to be substituted for cuttingoils in a variety of slow-speed and heavy-duty machining operationswhich heretofore have required oil lubrication.

Any water-soluble homopolymer of ethylene oxide having an averagemolecular weight of not less than 100,000 may be employed in thepreparation of the water-base lubricating compositions of the invention.Particularly satisfactory results have been obtained by using watersoluble homopolymers of ethylene oxide having an average molecularweight of from 100,000 to 4,000,000. These high molecular Weightpolymers are generally prepared via the polymerization of ethylene oxidein the presence of a catalytic amount of an alkaline earth carbonate,such as strontium carbonate, barium carbonate, or calcium carbonate.X-ray diflraction patterns of these high molecular Weight polymers showthem to have a high degree of crystallinity. Although thesepoly(ethylene oxide) polymers may be employed over a very wide range ofconcentrations, they are preferably used in an amount in the range fromabout A to about percent by Weight of lubricating composition. Aparticularly satisfactory range for general use is from 1 to 2 percentby weight.

The high molecular weight poly(ethylene oxide)s may be incorporated ineither water-base chemical or in water-base soluble-oil lubricatingcompositions, both of which contain one or more boundary lubricants. Thewater-base chemical lubricating fluids are generally composed of a majoramount of water and a minor amount of a water-misicible chemicallubricating mixture which, in turn, contains a boundary lubricantsuflicient to impart chemical lubricity to the composition. Basically,the chemical lubricating mixture consists essentially of threecomponents, namely a boundary lubricant, a corrosion inhibitor, and anantifoam. Typical chemical lubricating mixtures are usually composed of(1) from 50 to 95 percent by weight of a water soluble boundarylubricant, such as the nonionic and anionic surfactants or mixtures ofboth types of surfactants, (2) from 1 to percent by weight of acorrosion inhibitor, such as borax; sodium nitrite; alkanolamines suchas diethylanolamine and triethanolamine; allranol amides such as thosemanufactured by the Geigy Chemical Corporation under the trade nameAlrosol; and condensation products of diethanolamine with fatty acidssuch as lauric acid, and (3) from about 0.01 to about 1 percent byweight of an antifoam, such as a dimethylpolysiloxane or similarsilicone antifoam or fatty acid esters or higher alcohols (e.g. methylstearate, tricresyl phosphate, C C alcohols). Although a large number ofanionic surfactants have been used as a boundary lubricant, includingphenolates, carboxylates, and sulfonates, particularly satisfactoryresults have been obtained by using Water-soluble soaps, such as sodiumoleate, as the boundary lubricant in the chemical lubricating mixture.Various other types of boundary lubricants, in particular the Watersoluble sulfurized fatty acids or their derivatives as Well aschlorinated hydrocarbons and fats, have also been used in the chemicallubricating mixture in conjuction with a surfactant, and when so usedare generally employed in amounts up to about 10 percent by weight ofthe chemical lubricating mixture. In addition to the three essentialcomponents, namely the boundary lubricant, corrosion inhibitor, andantifoam, the chemical lubricating mixture may also contain from 1 to 5percent by weight of a germicide, such as sodium o-phenyl-phenoxide ormethyl p-hydroxybenzoate, to stabilize it and the fluid in which it isemployed against fungal or bacterial growth.

Preparation of a basic chemical lubricating fluid, to which thepoly(ethylene oxide) is added to form the lubricating composition of theinvention, is accomplished by dissolving the chemical lubricatingmixture in from 20 to 100 parts by weight of water. Lacking hydrodynamiclubricity, the viscosity of these water-based chemical fluids is almostas low as that of water. Dissolving from /4 to 5 percent by weight of ahomopolymer of ethylene oxide having an average molecular weight rangingfrom 100,000 to 4,000,000 in the lubricating fluid not only increasesthe viscosity but contributes hydrodynamic lubricity to the composition,allowing it to be used as a lubricant for all types of metal-forming,grinding, and machining operations. Lubricating fluids, prepared byfurther diluting this composition with from about 10 to about 100 timesits weight of water, still possess adequate chemical and hydrodynamiclubricity for slow-speed or heavy-duty machining operations and areconsistently found to be superior lubricants to cutting oils.

Similarly, the lubricating properties of water-base soluble-oillubricating fluids are also improved when a small quantity of thepoly(ethylene oxide) is dissolved in the fluid. The water-basesoluble-oil lubricating fluids are generally composed of a major amountof water in which there is emulsified a minor amount of a soluble-oillubricant, the amount being suflicient to impart both cooling andchemical lubricity to the composition. The solubleoil lubricant consistsessentialy of three components, namely a mineral oil, an emulsifyingagent, and a coupling agent. Typical soluble-oil lubricants usuallyconsist of from to percent by weight of a petroleum oil, generally oilshaving viscosities at about Saybolt seconds at 100 F. and from 10 to 20percent of a combination of emulsifying agents and coupling agents.Satisfactory emulsifying agents include the fatty acid soaps,naphthenate soaps, and oil-soluble mahogany soaps as well as nonionic,anionic, and cationic emulsifiers, all of which also function asboundary lubricants. Coupling agents which may be used include alcohols,glycols, and glycol ethers. In addition to these three basic components(petroleum oil, emulsifying agent, and coupling agent), the solubleoillubricant may also contain small amounts of Water, antifoam, andgermicide.

A basic soluble-oil lubricating fluid is prepared by forming anoil-in-water emulsion of the soluble-oil lubricant in 10 to 50 parts byweight of water. The addition to this fluid of from A to 5 percent byweight of a homopolymer of ethylene oxide having an average molecularwei ht ranging from 100,000 to 4,000,000 increases the viscosity of thefluid and contributes hydrodynamic lubricity to it, transforming it intoan improved lubricating composition for any type of metal-forming,grinding, or machining operation. This composition may be furtherdiluted, in turn, with Water without materially diminishing itslubricating properties.

The following non-limitative examples are illustrative of the water-baselubricating compositions of the invention. Many modifications will beobvious to those skilled in the art without departing from the inventiveconcept.

Example 1 Water-base chemical lubricating compositions which containonly boundary lubricants have generally proved to be inferior tocompounded cutting oils for many types of slow-speed or heavy-dutymachining operations, notably threading, tapping, and breaching, eventhough the waterbase lubricants are known topossess excellent extremepressure, antiweld and antiwear properties and to be more efficientcoolants than cutting oils. The addition of only a small quantity of apoly(ethylene oxide) having an average molecular weight of not less than100,000 to Waterbase lubricating composition, the quantity of thepolymer being suflicient to contribute hydrodynamic lubricity to themixture, improves the lubricating properties of the Water-base fluid toa point Where it is superior to cutting oils when used in metal-forming,grinding, and machining operations.

A water-base chemical lubricating composition was prepared by dissolving4 parts by weight of sodium oleate, 1.5 parts by weight of sodiumnitrite, and 0.1 part by weight of a dimethylpolysiloxane antifoam in92.25 parts by weight of water, the boundary lubricant (sodium oleate)imparting chemical lubricity to the composition. To contributehydrodynamic lubricity to the composition, 1.5 parts by weight of ahomopolymer of ethylene oxide having an average molecular weight of3,500,000 ($300,000) were dissolved in the aqueous lubricatingcomposition. A germicide, sodium o-phenylphenoxide, in the amount of0.15 part by weight, was then added to the composition to stabilize itagainst fungal or bacterial growth. The resultant water-base lubricatingcomposition possessed both chemical and hydrodynamic lubricity and couldbe used directly, or further diluted with water and then used, as alubricant for metal-forming, grinding, and machining operations.

Lubricating fluids, prepared by diluting the above composition withwater, still possessed adequate hydrodynamic lubricity for slow-speed orheavy-duty machining operations and were found to be superior lubricantsto cutting oils when employed in various machining and grindingoperations.

Example 2 The lubricating properties of water-base soluble-oillubricating compositions, which are composed primarily of stabilizedoil-in-water emulsions of a petroleum oil and a boundary lubricant, arealso improved when small quantities of a poly(ethylene oxide) having anaverage molecular weight of not less than 100,000 are dissolved in thecomposition.

A water-base soluble-oil lubricating composition was prepared byemulsifying 7.65 parts by weight of a petroleum oil having a viscosityof 100 Sayholt seconds at 100 F. in 90 parts by weight of water, using0.9 part by weight of mahogany soap and 0.18 part by weight of sodiumoleate as emulsifying agents, and 0.18 part by weight of a diethyleneglycol ethyl ether as a coupling agent. The emulsifying agents, mahoganysoap and sodium oleate, imparted chemical lubricity to the emulsifyingcomposition. A small amount of a dimethylpolysiloxane antifoam and of agermicide (e.g. sodium o-phenylphenoxide) in the amount 0.01 part byweight each, were added to the emulsified composition to stabilize itagainst foaming and bacterial growth respectively. To imparthydrodynamic lubricity, 1 part by weight of a homopolymer of ethyleneoxide having an average molecular weight of about 200,000 was dissolvedin the aqueous emulsion. The resultant emulsified water-base lubricatingfluid possessed both chemical and hydrodynamic lubricity and could beused in place of cutting oils for metal-forming, grinding, and machiningoperations.

The Water-base lubricating compositions and fluids of the invention,possessing both chemical and hydrodynamic lubricity, have proved to beespecially effective lubricants for all types of metal cutting,including threading, tapping, and broaching operations, particularlywhere there is an appreciable depth of cut.

In the foregoing examples of the invention, homopolymers of ethyleneoxide having an average molecular weight of not less than 100,000 wereused successfully to impart hydrodynamic lubricity to water-base chemicaor soluble-oil lubricating compositions. Similar advantages are alsoobtained when other water-soluble or water-dispersible polymers capableof contributing hydrodynamic lubricity are employed in the lubricatingcomposition in place of or in addition to these homopolymers of ethyleneoxide.

I claim:

1. A water-base fluid lubricating composition adapted to provide, upondilution with water, a lubricating fluid suitable for use inmetal-forming, grinding, and machining operations, comprising a majoramount of water, from 0.5 to 9.5 percent by weight of a boundarylubricant, and from about A to about 5 percent by weight of ahomopolymer of ethylene oxide having an average molecular weight of from100,000 to 4,000,000 to contribute hydrodynamic lubricity to thecomposition.

2. A water-based fluid lubricating composition adapted to provide, upondilution with water, a lubricating fluid suitable for use inmetal-forming, grinding and machining operations, comprising a majoramount of water, from 0.5 to 9.5 percent by weight of a boundarylubricant, and from about A to about 2 percent by weight of ahomopolymer of ethylene oxide having an average molecular weight of from100,000 to 4,000,000 to contribute hydrodynamic lubricity to thecomposition.

3. A water-base fluid lubricating composition adapted to provide, upondilution with water, a lubricating fluid suitable for use inmetal-forming, grinding, and machining operations, comprising from aboutto about 95 percent by weight of water, from about 1 to about 20 percentby weight of a Water-miscible chemical lubricating mixture consistingessentially of (a) from about 50 to about 95 percent by weight of aboundary lubricant, (b) from about 1 to about 10 percent by weight of acorrosion inhibitor, and (c) from about 0.01 to about 1 percent byweight of an antifoam, and from about A to about 5 percent by weight ofa homopolymer of ethylene oxide having an average molecular weight offrom 100,000 to 4,000,000 to contribute hydrodynamic lubricity to thecomposition.

4. A water-base fluid lubricating composition adapted to provide, upondilution with water, a lubricating fluid suitable for use inmetal-forming, grinding, and machining operations, comprising from aboutto about percent by weight of water, from about 1 to about 10 percent byweight of a water-miscible chemical lubricating mixture consistingessentially of (a) from about 50 to about 95 percent by weight of aboundary lubricant, (b) from about 1 to about 10 percent by weight of acorrosion inhibitor, and (c) from about 0.01 to about 1 percent byweight of an anitfoam, and from about A to about 5 percent by Weight ofa homopolymer of ethylene oxide having an average molecular weight offrom 200,000 to 3,800,000 to contribute hydrodynamic lubricity to thecomposition.

5. A water-base fluid lubricating composition adapted to provide ametal-cutting fluid upon dilution with water, comprising from about 85to about 95 percent by weight of water, from about 1 to about 10 percentby Weight of a water-miscible chemical lubricating mixture consistingessentially of (a) from about 50 to about 95 percent by weight of awater-soluble surfactant boundary lubricant, (b) from about 1 to about10 percent by weight of a corrosion inhibitor, and (c) from about 0.01to about 1 percent by weight of an antifoam, and from about A to about 2percent by weight of a homopolymer of ethylene oxide having an averagemolecular weight of 200,000 to contribute hydrodynamic lubricity to thecomposition.

6. A water-base fluid lubricating composition adapted to provide ametal-cutting fluid upon dilution with water, comprising from about 85to about 95 percent by weight of water, from about 1 to about 10 percentby weight of a Water-miscible chemical lubricating mixture consistingessentially of (a) from about 50 to about 95 percent by weight of awater-soluble surfactant boundary lubricant, (b) from about 1 to about10 percent by weight of a corrosion inhibitor, and (c) from about 0.01to about 1 percent by weight of an antifoam and from about A to about 2percent by Weight of a homopolymer of ethylene oxide having an averagemolecular weight of 3,500,000: 300,000 to contribute hydrodynamiclubricity to the composition.

7. An emulsified water-base fluid lubricating composition adapted toprovide, upon dilution with water, a lubricating fluid suitable for usein metal-forming, grinding, and machining operations, comprising a majoramount of water, from about 5 to about 50 percent by weight of asoluble-oil lubricant consisting essentially of a petroleum base oil, anemulsifying agent, and a coupling agent, and from about A to about 5percent by weight of a homopolymer of ethylene oxide having an averagemolecular weight of from 100,000 to 4,000,000 to contribute hydrodynamiclubricity to the composition.

8. An emulsified water-base fluid lubricating composition adapted toprovide, upon dilution with water, a lubricating fluid suitable for usein metal-forming, grinding, and machining operations, comprising fromabout 80 to about 90 percent by weight of Water, from about to about 20percent by weight of a soluble-oil lubricant consisting essentially offrom about to about percent by weight of a petroleum base oil, and fromabout 10 to about 20 percent of an emulsifying agent and a couplingagent, and from about /4 to about 5 percent by Weight of a homopolymerof ethylene oxide having an average molecular weight of from 200,000 to3,800,000 to contribute hydrodynamic lubricity to the composition.

References Cited by the Examiner UNITED STATES PATENTS 1,773,123 8/1930Sullivan 252-495 2,563,588 8/1951 Dixon 25249.5 2,825,693 3/1958Beaubien et al. 25249.3 2,914,491 11/1959 Bailey 252-52 OTHER REFERENCESDANIEL E. WYMAN, Primary Examiner.

C. F. DEES, Examiner.

1. A WATER-BASE FLUID LUBRICATING COMPOSITION ADAPTED TO PROVIDE, UPONDILUTION WITH WATER, A LUBRICATING FLUID SUITABLE FOR USE INMETAL-FORMING, GRINDING, AND MACHINING OPERATIONS, COMPRISING A MAJORAMOUNT OF WATER, FROM 0.5 TO 9.5 PERCENT BY WEIGHT OF A BOUNDARYLUBRICANT, AND FROM ABOUT 1/4 TO ABOUT 5 PERCENT BY WEIGHT OF AHOMOPOLYMER OF ETHYLENE OXIDE HAVING AN AVERAGE MOLECULAR WEIGHT OF FROM100,000 TO 4,000,000 TO CONTRIBUTE HYDRODYNAMIC LUBRICITY TO THECOMPOSITION.